AV News 200 - May 2015
Where inaccurate exposure has blocked subtle detail then these sliders may
help recover such detail. The effects of slider movements within the
'Shadow/Highlights' tool can be visually observed in real time. However
before making any adjustments it's useful to understand the relationship of
each slider to other sliders within the same group.
Whilst 'Amount' and 'Tone' (tonal width) are expressed as percentage this
is not the case with 'Radius', which is always expressed as number of pixels.
Radius controls the size of the local neighbourhood around each pixel.
Neighbouring pixels are used to determine whether a pixel sits within the
shadows or highlights parameters. Moving the Radius slider to the left
specifies a smaller area i.e. less pixels, and moving it to the right specifies a
larger area of more pixels. The optimum setting for number of local
neighbourhood pixels depends very much on the individual image including
image size, i.e. 30 pixels of a 1920 x 1080 image is very much smaller by area
percentage than 30 pixels on a 1400 x 1050 or 1024 x 768 image. Therefore
some experimentation with different Radius settings may be required to
obtain the best result for your particular image. If the 'Radius' is set too large
then adjustment using the 'Amount Slider' may effect too much of the image
rather than just the required highlight or shadow area. As a rule of thumb start
with the default 30 pixels then adjust up or down as necessary, but ensure
that midtones remain unaffected.
Amount is almost self-explanatory, it's the amount of correction applied to
place more tone and detail into the highlights, or conversely to lighten the
darkest shadow areas enabling blocked detail to show through.
Tone (tonal width) by default this is set to a value of 50% i.e. midtones. For
most adjustment to either Shadow or Highlight this proves a very good
starting point and may not require further adjustment. However by moving this
slider either left or right shifts the balance of the tonal range effected by the
'Amount' slider. Once again this is a matter of experimenting to find the most
appropriate setting for a particular image.
In the lower third of the 'Shadow/Highlight Control Panel' sits two other
sliders under the general heading of 'Adjustments'. One named 'Color' and
the other 'Midtone'. These two sliders should normally be used after making
adjustments to Shadow or Highlights, and only if necessary, because they
effect the colour and midtone balance of the 'adjusted' areas whilst having no
effect on other areas.
It's always good practice to make a copy layer from the original (Ctrl + J)
on which to carry out edits, this maintains the integrity of the original and
saves edits on separate layers within a .psd file for future editing. Where
adjustments to Shadow or Highlight area are required it's wise to convert the
copy layer into a 'Smart Object', doing so enables adjustments to be changed
after a .psd file is saved then re-opened. Note; simple overall exposure
adjustments using the 'Exposure Control Panel' are not enabled on a 'Smart
Object' layer, however all controls within the 'Shadow/Highlight Control Panel'
are fully enabled in either 8 or 16 bit mode, but not in 32 bit mode.
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